This invention is generally directed to a process for the preparation of colorants, and more specifically, the present invention relates to processes for obtaining colorants that can be selected for dry toners and inks, such as ink jet inks. In embodiments, the present invention relates to the chemical treatment of colorants in liquid carbon dioxide, or supercritical fluid (SCF) carbon dioxide. The present invention relates in embodiments to the preparation of colorants like pigments selected for toners, which toners are useful for the development of images in xerographic imaging and printing methods. More specifically, the present invention relates to the preparation of colorants in a supercritical fluid, such as supercritical carbon dioxide. With the processes of the present invention no or minimal solvent residue results, there are enabled colorant products wherein no or minimal solvent waste exists, colorant agglomeration is avoided, or minimized, and color degradation is avoided, or minimized. Also, there is enabled with the processes of the present invention complete and clean removal of the carbon dioxide solvent from the colorant product without costly and cumbersome solvent separation methods. Further, the use of a carbon dioxide medium eliminates the need for solvent disposal since, for example, at atmospheric conditions, carbon dioxide spontaneously separates from solids, thus no liquid waste is generated. Also, some treating agents, or components, such as fluorosilanes which are useful for modifying the surface characteristics (such as surface energy, contact angle, etc.) of pigments, are more soluble in carbon dioxide as compared to their solubility in conventional liquid hydrocarbon solvents. One specific example of a potentially advantageous medium for the colorant preparation is supercritical fluid (SCF) carbon dioxide, with the critical temperature of CO.sub.2 being about 31.degree. C. Since an operating temperature of approximately 31.degree. C. or higher could render the solution into the SCF regime, operation of the process is potentially more economically viable than operation in the liquid phase of carbon dioxide or in conventional liquids in view of the higher reactivity of treating reagents at higher temperatures. What primarily distinguishes a supercritical fluid from a vapor is that no meniscus can be discerned in the fluid phase regardless of the pressure applied.